Tag Archives: PTFE

Solving High-Pressure, High Eccentricity Seal Issues

Facing challenges, head-on is what Vanseal does every day – which is why their customers trust them to deliver tested and proven, material and design solutions that improve the performance of their seals, no matter how tough the environment.

High-Pressure, High Eccentricity Seal Solution Demonstrates 50% Improvement

– On pressure and side-load performance of a fluid application

Recently, a customer was having difficulty with a seal failure on apicture of leoader fluid power application. The high-pressure, high-eccentricity seal operates in conditions up to 200,000 pv at 3000 psi and could not exceed maximum shaft deflection of 0.005″.

Vanseal works with these types of seal applications frequently and used a Unitized Seal that uses several components to address each of the various sealing challenges.

Vanseal’s solution for its high-pressure, high-eccentricity seal incorporated these key elements:

  • Primary Seal Lip – Made from a high-modulus elastomer, to reduce lip extrusion and inversion under pressure, better distributing high-pressure forces to enhance sealing
  • Machined PTFE Backup Lip – Used to reduce the risk of extrusion and inversion of the Primary Seal Lip
  • Support Washer – Designed to close the extrusion gap between the seal ID and shaft under high, shaft-deflection conditions
  • Excluder Lip – Works to keep contaminants from entering the assembly system
  • Metal Case – Serves as a carrier for the seal components creating a single unit to install, and thus reducing instances of installation errors caused by multi-piece installations and reducing individually purchased and inventoried items.

Vanseal has been manufacturing highly specialized seal components for over 60 years

  • Sealing systems are tricky and using a stock seal manufactured for typical high-pressure applications may not be enough to absorb high-shaft deflection.
  • Our experienced engineers have in-depth knowledge on how to address these difficult sealing challenges.
  • Along with engineering, we maintain the highest standards in quality testing and manufacturing methods.

The original article can be found on Vanseal’s website.

To learn more about Vanseal’s products, speak to a Gallagher representative today by calling 1-800-822-4063

Lower Friction, Weight, and Emissions – The Freudenberg BlueSeal

Freudenberg-NOK Sealing Technologies has begun supplying innovative, lightweight radial shaft seals to a major Detroit-based vehicle manufacturer for installation on the V6 and V8 engines powering its newest pickup trucks and sport utility vehicles (SUVs).  Enter the Freudenberg BlueSeal.

The BlueSeal, part of Freudenberg’s award-winning Low Emission Sealing Solution (LESS) portfolio of engine, transmission and E-Mobility product solutions, provides significant weight, friction and installation advantages over traditional radial shaft seals. Under the contract, Freudenberg-NOK will produce more than 2 million BlueSeals annually. Production is expected to increase further to more than 4 million units annually with orders from additional customers.

40 percent lighter and 50 percent less space to install

From turbocharged engines and 10-speed transmissions topicture of blueseal electrified and electric vehicle systems, the propulsion technologies on display at the 2019 North American International Auto Show (NAIAS) offer evidence that fuel economy, emissions and performance are still top of mind with manufacturers and consumers alike. Freudenberg’s BlueSeal offers customers a way to help achieve better fuel economy and lower emissions in large displacement internal combustion and turbocharged engines. The BlueSeal is 40 percent lighter than conventional radial shaft seals and requires 50 percent less space to install.

“Vehicle manufacturers are looking at every possible way to increase fuel efficiency and reduce weight, especially in trucks, SUVs and turbo-charged performance vehicles,” said Jeff Nelson, vice president, Automotive Sales, Freudenberg-NOK. “Even the smallest components can have a dramatic impact on the function and efficiency of vehicle powertrains.”

The BlueSeal is made of a single material – a steel-reinforced Polytetrafluoroethylene (PTFE) – designed to withstand harsh engine fluids while providing an axial space reduction, which allows manufacturers to downsize the engine. The seal has a low-friction Power Optimized Polytetrafluoroethylene (POP®) lip design that insures smaller dissipation loss, reduces the temperature in the contact area between the seal and shaft and performs flawlessly under different engine conditions.

Dual product development strategy for the automotive industry

The BlueSeal increases durability through its perfect sealing behavior and has a higher resistance to pressure than traditional seal designs. Its R-Tight® technology results in near-zero air leaks during assembly tests, allowing manufacturers to isolate other potential leak paths in the system.

Freudenberg is pursuing a dual product development strategy that supports continued development of advanced materials and components for internal combustion powertrain applications while pursuing new technologies that address emerging challenges associated with alternate mobility options like lithium-ion batteries and fuel cells. The BlueSeal, like many of Freudenberg’s LESS products, offers system benefits in both arenas.

“The automotive industry is undergoing profound transmission and driveline changes,” Nelson said. “It is our job to provide customers with exceptional component solutions that address the needs of all mobility platforms regardless of the fuel they use. The need to harness energy effectively and efficiently is a common denominator across our development efforts.”


The original article can be found on Freudenberg’s website.

To learn more about Freudenberg products, speak to a Gallagher representative today by calling 1-800-822-4063

Case Study: Replacing U-Cups with PTFE Spring Energized Seals in High Temperature Applications

Being commodity items, U-Cups are readily available in a number of materials and can be found on-the-shelf from multiple distributors and manufacturers in many standard sizes.

Named for the shape of their cross-section, a U-Cup’s design will be pressure energized increasing sealing effectiveness when compared to a standard O-Ring.

This means as pressure increases, the sealing lips are continually forced into the mating hardware surface, ensuring good contact at all times.

The simple and easily moldable design is an effective sealing solution to many systems in both hydraulic and pneumatic applications. Modifications in lip thickness and inclusion of an O-Ring Energizer can tailor sealing loads and wear life to specific situations.Spring Seal and U Cup

A key advantage to an elastomeric U-Cup is the relatively small and simple hardware space needed. Because of their flexible compounds, most U-Cups can be installed in a solid gland configuration.

A basic ID or OD groove is all you need for proper seal retention. Plus, no special tools or considerations need to be taken for correct installation.

U-Cups are available in many of the same compounds as standard O-Rings such as Nitrile, Fluorocarbon, and EPDM, but polyurethanes may be the most common material.

Urethane provides a good combination of elasticity/pliability and toughness. Therefore, it exhibits good sealing characteristics as well as, durability and wear resistance.

These desirable qualities make U-Cups an optimal solution for many sealing systems across multiple industries and they can be found in countless standard products. But Eclipse is approached many times a year with customers pushing the limits of standard U-Cups and in need of better solutions.

The Client’s Issue

Eclipse was approached by a leading pneumatic cylinder manufacturing seeking a sealing solution for a unique application.

While U-Cups typically provide optimal sealing performance in pneumatic cylinders, this application presented a difficult challenge.

The air cylinder was to be used as an actuator for a latch on a large industrial oven. While pressures, speeds, and cycle times were nothing out of the ordinary, the temperature at which it had to operate at was — a continuous 500°F.

Continue reading Case Study: Replacing U-Cups with PTFE Spring Energized Seals in High Temperature Applications

Garlock Case Study: Poultry Processing: KLOZURE® ISO-GARD®

Poultry Processing: KLOZURE® ISO-GARD®

ISO-GARD bearing isolators offer exceptional bearing protection for pumps, motors, and bearing supported industrial equipment under the harshest conditions.

ISO-GARD products are constructed using a filled PTFE material which provides excellent chemical resistance.

INDUSTRY

Food – Poultry Processing

CUSTOMER

A diversified food processing company, with facilities located
throughout the US.

BACKGROUND

The customer had persistent problems with sealing the bearings inpicture of iso gard their non-metallic feather picker housings. Using standard lip seals, and with a monthly maintenance program, they still encountered frequent failures. With 72 assemblies (each with two sealing locations) this had a detrimental effect on manufacturing efficiency, and placed a significant burden on the maintenance teams.

CHALLENGES FACED

Poultry feathers were getting under the lip seals and into the bearing housing, causing frequent and unexpected failures. Daily wash-downs also used a chemical cleaning solution that could also damage the bearings if not sealed correctly. Additionally, there was limited space available for any modification of sealing element.

Meat processing environments are highly regulated by the FDA, so any manufacturing changes must be carefully controlled. Therefore the customer required close support to ensure that any changes could be implemented with full confidence.

Continue reading Garlock Case Study: Poultry Processing: KLOZURE® ISO-GARD®

EagleBurgmann’s Patented SeccoLip

A patented lip design and the patented combination of PTFE sealing lip and sliding bearing in the lip seal element provide the new dry running seal “SeccoLip” from EagleBurgmann with particularly high flexibility. These technical features help the lip seal compensate directly and safely radial deflections of the shafts in agitators, mixers and reactors.

The sliding bearing tracks the complete lip seal element to the shaft movements. Since the lip and bearing are in one element, the sealing gap between the rotating shaft and the sealing lip remains virtually constant and the seal remains tight over the long term. Compensating elements such as O-ring, expansion washer or metal bellows are not required for reliable operation.

The modular seal was specifically designed for the operating conditions in the chemical, pharmaceutical, food industry as well as in water and wastewater technology. One or more sealing elements are combined in different possible arrangements to comply with the requirements.

Connections for a supply system are available. Due to the design features, a rolling bearing is not necessary but is optionally available.

The cartridge design makes the SeccoLip easy to install and safe to use. It is particularly suitable for a sliding velocity of up to 2 m/s (6 ft/s) and a pressure range of -1 to 6 barg.

The seal complies to ATEX, FDA and TA-Luft.

Watch the SeccoLip video here:


If you have questions about using any of EagleBurgmann’s products, visit their website: EagleBurgmann.  Or call +1 (713) 939 9515

Compression Packing: A Look Beyond the Standard Stuffing Box

Compression Packing

How this application fits as a versatile solution.

Stem packing is a familiar product. The most common type is braided compression packing. Braided packing is used in a wide range of applications. Depending on the service, construction materials can be as diverse as plants or animal derivatives, mineral fibers or synthetic plastics and even metal. The process of cutting rings from rope packing, inserting them into a stuffing box and torquing them to the right density is common, but it is not always the best choice.

Another widely used manufacturing method is die-molding. It is the process of wrapping a material around a mandrel, placing it in a die and preforming it to make a seal. Using these and other manufacturing technologies, packing is found to work in applications as different as aerospace, heavy trucking and power generation. A review of some unusual applications demonstrates the versatility of compression packing as a sealing solution.

The Origin of Packing

Compression packing is an ancient technology dating back more than 5,000 years. Boats and ships used a rudder as a steering mechanism. The rudder shaft penetrates the hull of the vessel below the water line, so water can leak into the bilge. Ancient sailors, using the top technology of the day, would take pieces of clothing, sail cloth and rope, cover it with animal fat or wax and stuff it into the gap around the shaft. Eventually, a box was secured around the shaft and a gland, which could be tightened to compress the packing material, was created to improve sealing and longevity. The terms compression packing, stuffing box and gland come from these early sailors.

Compression Packing

Over time, many improvements in packing construction and materials were made. Packing today can be made of flax, Kevlar, polytetrafluoroethylene (PTFE), graphite or metal. It typically has a square cross-section and is sold in precut rings or in large coils, as shown in Image 1. Synthetic aramid fibers are abrasionresistant and can handle higher temperatures and shaft speeds. PTFE has excellent lubricity and chemical resistance. Graphite coupled with mica or an aramid fiber can stave off the heat generated by a rotating shaft and provide long life in challenging applications.

Die-Formed Packing

Die-formed compression packings are excellent in terms of sealing Picture of a die formed ringperformance and reliability and offer a wide range of long-term, low-emission and low maintenance products. See Image 2.

Not only are die formed rings easier and quicker to install, but the  pre-compression increases the density of each ring and reduces the gland loads necessary to seat and compress multiple rings in the stuffing box. The result is lower friction on the shaft or the spindle, with improved sealing performance and a longer life.

Factor in STAMPS

As mentioned in an article previously published by the Fluid Sealing Association, (Sealing Sense, Pumps & Systems, March 2005), there are several key factors to consider when choosing the right packing. They include:

  • size or stuffing box bore
  • temperature inside the stuffing box application: whether it’s a pump, valve, mixer, refiner, process, characteristics such as pH level and chemical compatibility
  • motion: rotary, helical or reciprocal
  • pressure inside the stuffing box
  • surface speed expressed in feet per minute or meters per second

Keeping this in mind, here are some applications to consider when you are going way beyond the typical stuffing box: Continue reading Compression Packing: A Look Beyond the Standard Stuffing Box

A Guide to Elastomer Technology in Mechanical Seals

Elastomer Technology in Mechanical Seals

Evaluate properties of rubber during installation and seal life.

Elastomers (or rubbers) are a ubiquitous family of materials whose use stretches across nearly the entire range of mechanical seal designs.  From plant-sourced natural rubber, so named by John Priestly in 1770 for its utility in rubbing away pencil graphite, to petroleum-sourced synthetic rubber first developed around the turn of the 20th century, the “elastomer” and their properties are familiar but should not be overlooked—especially when dealing with mechanical seals.

How Elastomers Work in Mechanical Seals

Rubber seals come in a variety of profiles—O-rings, cup gaskets, bellows diaphragms, sealing/wiper lips and many others. They are classified as either static or dynamic and create positive pressure
against surfaces to eliminate or control the leakage of liquids and/or gases while preventing the entrance of external contaminants such as dust and dirt. Static sealing occurs between adjacent surfaces with no relative motion, such as between the pump casing and cover. Due to frictional wear and heat generation, dynamic sealing is less straightforward, occurring between adjacent surfaces that are continuously or intermittently moving relative to another, such as between the pump casing and shaft.

In mechanical face seals, elastomers tend to take second chair because the primary seal—the dynamic seal between the housing and rotating shaft—is achieved by sliding contact between the pair of stiffer, lapped-flat sealing faces, one stationary in the housing and one rotating with the shaft. In many designs, rubber provides the secondary seal between each seal face and adjacent surface. One seal face is fixed and sealed statically using an O-ring or cup gasket. The other is spring-loaded and requires a semi-dynamic seal to accommodate some axial play, such as a dynamic O-ring in pusher-type mechanical face seals or elastomeric bellows in nonpusher ones. These semi-dynamic applications (involving flexing and sliding of the elastomer) can be critical for maintaining proper contact between the faces through face wear, shaft movement, etc.

Although the seal face pair tends to be the most critical design feature, mechanical face seals are  often used in the most demanding applications.

Rubber technology features prominently in radial lip seals, where typical applications have lower pressurevelocity (PV) values relative to those involving mechanical face seals. Still, the flexible elastomer lip must handle considerable relative motion in the form of shaft/bore rotation, reciprocation or a combination of both. In addition to standard designs and sizes, numerous customizations and proprietary approaches exist. The simplest designs rely on a single rubber lip’s inherent resiliency, although common enhancements include multiple sealing lips, a circumferential garter spring installed in a groove over the sealing lip to maintain contact with the shaft, and an auxiliary wiper lip or “excluder” to prevent abrasive dust or debris from compromising the primary sealing surface. For improving service life and performance in rotary applications, unidirectional or bidirectional hydrodynamic pumping aids can be added in the form of custom-shaped extrusions on the backside of the sealing lip to return leaked fluid to the sealing interface, increase lip lubrication and lower operating temperatures.

Diagram of secondary, dynamic elastomeric seals in mechanical face seals.

Benefits of Rubber

The definition of an elastomer provides initial insight into where rubber gets its resilient sealing quality: “a macromolecular material which, in the vulcanized state and at room temperature, can be stretched repeatedly to at least twice its original length and which, upon release of the stress, will immediately return to approximately its original length.”

When the rubber is squeezed by the adjacent surfaces of the clearance gap to be sealed, it has the characteristic
properties of malleably deforming and taking the shape of each  surface in response to the stress and applying a force back against the surfaces in its attempt to return to its original dimensions. Elastomers consist of large molecules called polymers (from the Greek “poly” meaning “many” and “meros” meaning “parts”), which are long chains of the same or different repeating units, called monomers, usually linked together by carbon-carbon bonds (the
most notable exception being silicone elastomers, which are linked by silicon-oxygen bonds). Soft and hard plastics are also composed of polymers. However, the regularity of the monomers in their polymer chains allows neighboring segments to align and form crystals, making the macromolecular plastic material rigid and inelastic.

One can prevent this crystallization by breaking up the regularity of the polymer chain, resulting usually in a viscous “gum” that is readily shaped into molds. At the molecular level, the polymer chains are similar to spaghetti-like strands flowing past each other.

During the process of vulcanization, Representatin of three polymer chains after formation of crosslinking via vulcanizationor curing, the viscous liquid is heated with sulfur or peroxides and other vulcanizing agents, and crosslinks form between polymer chains, tying them together with chemical bonds, converting the gum into an elastic, thermoset solid rubber that retains its shape after moderate deformation.

In addition to the selection and preparation of base polymer(s) and cure system ingredients, formulating the final rubber product, also known as compounding, involves five other broad categories of ingredients, which have percentage compositions expressed in parts per hundred rubber (phr). Fillers include various powders that thicken the polymer mixture, improve strength and resistance to abrasives, and reduce final cost. Plasticizers are oils and other liquid hydrocarbons that lower viscosity to ease processing, soften the final compound and in some cases improve low temperature performance. Process aids are specialized chemicals added in low concentrations to improve mixing, flow properties and final appearance.

Antidegradants protect the rubber from environmental attack. Finally, various miscellaneous ingredients may be added for special purposes, including foaming agents, dyes, fungicides, flame
retardants, abrasives, lubricants and electrically conductive particles. A simplified description of processing these ingredients includes mixing via tangential or intermeshing mixers, forming into desired shapes and vulcanizing into the final product.

Continue reading A Guide to Elastomer Technology in Mechanical Seals

How to Investigate Compression Packing Failure Modes

Over-tightening, excessive speed and improper installation can cause a system to falter.

In many respects, troubleshooting and failure analysis of compression packing materials is similar to the investigation of a crime scene. A good investigator knows how to gather clues from many different sources and put them together to understand what has happened. A good troubleshooter uses the same information gathering method, familiarizing themselves with the sealing materials, the process equipment and the systems where they are used.

Start by Interviewing Witnesses

The troubleshooter should seek information from the people who work with the equipment on a regular basis. Seal installers, maintenance personnel, operators, process engineers and others can all shed light on potential causes of failure. Some key questions should be:

  • How is failure defined? Some examples include excessive leakage, overheating, high rate of flush water consumption, excessive friction load and blowout.
  • Is this application the source of chronic seal failures, or was this an unexpected event?
  • Were there any changes to the seal material, the equipment or the overall process that preceded the failure?
  • Were there any system upsets or cleaning cycles that preceded the failure?
  • Can you describe the installation procedure?

Gather Information About the Victim

Knowing the limitations of the sealing product is a key step. The acronym “STAMPS” will help remember the key elements to ensure the right packing is selected for the application.

  • S: Size. Is the correct packing cross-section being used? Are the rings cut or formed to the correct length?
  • T: Temperature. Check the system temperature against the packing manufacturer’s established temperature ratings for the product.
  • A: Application. Some packings are made specifically for rotary equipment while others are intended for valves or static seals. Check to make sure the packing is suitable for the equipment where it is being used.
  • M: Media. This refers to the fluid being sealed. Check with the manufacturer or with compatibility charts to be sure the seal material is compatible with the media. If the media is slurry, abrasion-resistant materials may need to be specified. If the media is toxic, explosive or required to be contained within certain maximum allowable leakage requirements, then a packing must also be selected on the basis of its ability to seal at low leakage levels.
  • P: Pressure. Check the system pressure against the packing manufacturer’s established pressure ratings for the product.
  • S: Speed. Check the equipment speed against the packing manufacturer’s established surface speed ratings for the product. Surface speed is expressed in feet per minute or meters per second and not revolutions per minute.

Investigate the Crime Scene

When possible, observe the equipment while it is running. Can you see, hear, feel, smell or use a sensor to make observations? Smoke, vibration, grinding noises, the scent of burning fibers and system pressure fluctuations are only a few of the clues that can be noticed or measured while the equipment is up and running.

Examine the condition of the equipment. Most packings are robust seals that can handle less than perfect equipment condition, but there are limits to the amount of degradation they can withstand.

Valve stems and pump shafts or sleeves should be checked for scratches, corrosion pitting and general surface roughness. Rough surfaces can damage the sealing surface and result in excessive leakage and quick wear of the seal.

Extrusion of the seal material
Image 1. Extrusion of the seal material

Excessive clearances at the top or bottom of the stuffing box can lead to extrusion of the seal material and intrusion of large solid particle into the seal area (see image 1).

In severe cases, excessive clearance may result in a seal blowout.

Most packings are not meant to function as both a seal and a bearing. In rotating equipment, poor bearing condition may result in shaft runout that “wallows out” the inside diameter of the seal. Misalignment may result in shaft/stuffing box offset that causes one side of the packing set to be heavily compressed while the other side is compressed much more lightly. A similar side loading of a packing set can occur in large horizontally oriented valves where the packing is forced to bear the weight of the stem.

Check to make sure all the parts are in place. During the breakdown, repair and reassembly of equipment it is possible to misplace parts. Equipment might be put back into service without seat rings, bushings, lantern rings, O-rings and other parts that are essential to proper equipment operation.

Look at the seal and the equipment as a part of a big picture.

Consider how this piece of equipment is affected by other equipment and control devices in the system. For example, is there a downstream valve that creates pressure spikes in an upstream pump seal when the valve closes and the pump is still operating?

Continue reading How to Investigate Compression Packing Failure Modes

The Perfect Wave; The Gerromatic Rotary Seal

Gear motors, pumps and stirring units keep process material in constant motion in the process industry’s production facilities. A large number of shaft seals are used at drive shafts to keep liquids securely within the equipment. But leaks may be more likely to occur if the pressure acting on the seals becomes too great. Freudenberg Sealing Technologies has developed a new rotary seal, the Gerromatic, which has a wave-shaped sealing lip. This increases the maximum amount of pressure that can be applied. The sinusoidal contact path also reduces friction and provides self-cleaning, which extends operating life.

In the process industry, including the food and beverage sector, shaft seals used in equipment mostly have a rotation-symmetrical seal lip, which abuts the rotating shaft with a groove-like contact pattern. During wet-running, this can cause the medium to be displaced at the contact surface. The seal then runs in a more or less dry condition, leading to increased friction and higher temperatures. The increased friction increases wear and reduces the efficiency of the equipment. The accompanying rise in temperature is not desirable, especially when the process media are temperature-sensitive. If the seal lip is also exposed to high temperatures at high rotational speeds – for example, due to a process material that applies pressure to the seal lip in a vessel with a stirring unit below it – the lip can fold down on the low-pressure side, which would result in immediate leakage and the seal’s failure.

Continue reading The Perfect Wave; The Gerromatic Rotary Seal

What is ePTFE?

ePTFE - Bill Gore & his wife, VieveSince 1958, Gore has developed products that improve lives. At the center of these solutions is polytetrafluoroethylene (PTFE), a polymer with exceptional properties like high tensile strength, a low dielectric constant, UV resistance and many more. In 1969, the possibilities for PTFE expanded with Bob Gore’s discovery of expanded PTFE, or ePTFE.

In the years since, Gore has developed unparalleled expertise in manipulating ePTFE and other fluoropolymers. Gore’s engineers can change a material’s structure, shape, thickness and surface geometry, then pair it with complementary materials to provide the performance qualities required by the application and the customer. The resulting product can be strong or permeable, rigid or flexible, thin or thick — with many additional combinations of properties that can be applied to meet the end use requirements.

Since its very founding, Gore has been passionate about solving the complex challenges of their global customers. From the first suggestion of a product need, to its delivery to market, this passion is apparent in everything Gore does.

  • Curiosity: From keeping water off a person’s skin to preventing leaks from happening in chemical containers, Gore listens to their customers and analyze the challenges to determine the underlying problem.
  • Competency: Gore determines how they can apply their expertise in fluoropolymer science to deliver solutions that are valued and differentiated from the competition.
  • Commitment: Gore rigorously tests their products to ensure they deliver failure-free performance and suit their customers’ needs and applications, the first time and every time.

Continue reading What is ePTFE?